The present invention relates to a shock absorber for absorbing energy generated when a moving workpiece collides with a movement end and stops.
A shock absorber for absorbing and cushioning energy generated when a workpiece collides with a movement stopper member and stops is already known without the necessity of citing an example.
FIG. 3 shows a known shock absorber having a stopper collar for positioning and the shock absorber 1 has an absorber main body 2 and the stopper collar 3.
The absorber main body 2 is screwed in a frame 5 through a thread 2a on an outer peripheral face of the absorber main body 2 such that the absorber main body 2 can move forward and rearward in a moving direction of a workpiece 6. The stopper collar 3 is screwed on a tip end side (a collision side of the workpiece 6) of the thread 2a of the absorber main body 2 such that the stopper collar 3 can move forward and rearward.
Both the absorber main body 2 and the stopper collar 3 can be fixed in arbitrary positions in the moving direction of the workpiece 6 by locknuts 2A and 3A screwed on the thread 2a of the absorber main body 2.
The shock absorber 1 has a damper rod 4 for absorbing energy generated when the workpiece 6 collides at a tip end of the absorber main body 2 and the damper rod 4 projects toward the workpiece further than a tip end of the stopper collar 3 screwed on the absorber main body 2.
In the shock absorber 1, because the stopper collar 3 moves forward and rearward integrally with the absorber main body 2 if the locknut 2A is loosened and the absorber main body 2 is moved forward and rearward in the moving direction of the workpiece 6, a stop position (a distance d1 between the workpiece 6 and the frame 5) of the workpiece 6 can be adjusted and the absorber main body 2 is fixed in the position by tightening the locknut 2A.
Because the length d2 by which the damper rod 4 projects from an end face of the stopper collar 3 changes if the locknut 3A is loosened and the stopper collar 3 is moved forward and rearward along the absorber main body 2, the operating range of the shock absorber for absorbing collision energy, i.e., absorbing performance of the shock absorber can be adjusted and the stopper collar 3 is fixed in position by tightening the locknut 3A.
However, in this shock absorber 1, because the stop position (the distance d1) of the workpiece 6 changes if the operating range is adjusted by moving the stopper collar 3 forward and rearward along the absorber main body 2, it is necessary to adjust the stop position again.
Furthermore, because the stopper collar 3 is screwed on the tip end side of the thread 2a of the absorber main body 2, there is a limit as to reduction the of the stop distance d1 of the workpiece 6 with respect to the frame 5.
On the other hand, FIG. 4 shows another structure of a known shock absorber. The shock absorber 11 has an absorber main body 12 and an adjustment bolt 13. The body 12 and bolt 13 are separately screwed in the frame 5 through threads formed on their outer peripheral faces such that the body 12 and bolt 13 are oriented so as to be parallel to each other and can move forward and rearward with respect to a moving direction of a workpiece 6. The body 12 and bolt 13 can be fixed in arbitrary positions in the moving direction of the workpiece 6 by locknuts 12A and 13A screwed on the threads.
Because the absorber main body 12 and the adjustment bolt 13 are provided separately and parallel to each other in the shock absorber 11, it is possible to reduce the stop distance d1 of the workpiece 6 with respect to the frame 5 as compared with the shock absorber 1 shown in FIG. 3. frame 5 as compared with the shock absorber 1 shown in FIG. 3.
However, because the distance d2 between an end face of the adjust bolt 13 and a tip end of a damper rod 14 changes if the adjustment bolt 13 is moved forward and rearward to adjust the stop distance d1 of the workpiece 6, it is necessary to adjust an operating range for absorbing collision energy again.
Therefore, it is necessary to separately carry out adjustment of the stop position of the workpiece 6 and adjustment of the operating range and such adjusting operations are burdensome.
Moreover, because the absorber main body 12 and the adjustment bolt 13 are disposed in different positions in parallel to each other and are not coaxial with each other, the workpiece 6 may be inclined when the workpiece 6 collides with the absorber main body 12 or the adjustment bolt 13.
It is an object of the present invention to provide a shock absorber for easily adjusting a stop position of a workpiece that collides with a movement end and stops and energy absorbing performance.
To achieve the above object, a shock absorber according to the present invention comprises a stopper for determining a stop position of a workpiece by directly or indirectly coming into contact with the workpiece that has reached a transfer end and an absorber main body for absorbing and cushioning collision energy generated when the workpiece comes into contact with the stopper, wherein the stopper has at a tip end thereof a contact portion with which the workpiece comes into contact and is mounted on a workpiece transferring device such that the stop position of the workpiece can be adjusted, and the absorber main body has at a tip end thereof a shock-absorbing portion for absorbing the collision energy and is mounted to the stopper such that the absorber main body is coaxial with the stopper and that a relationship between positions of the contact portion at the tip end of the stopper and the shock-absorbing portion with respect to each other can be adjusted.
In the shock absorber of the invention having the above structure, the stop position of the workpiece can be adjusted by moving the stopper forward and rearward. In this case, the absorber main body is mounted to the stopper, moves with the stopper, and does not move with respect to the stopper. Therefore, the operating range for absorbing the energy by the absorber main body does not change.
The operating range is adjusted by moving the absorber main body forward and rearward with respect to the stopper. At this time, although the absorber main body moves with respect to the stopper and a distance between the contact portion and the shock-absorbing portion changes, the stopper does not move. Therefore, the stop position of the workpiece does not change.
Therefore, because adjustment of the stop position of the workpiece by the stopper and adjustment of the operating range of energy absorption by the absorber main body can be carried out separately, adjusting operations are easy.
According to a concrete embodiment of the invention, the stopper has a cylindrical shape, threads are respectively formed on an inner periphery and an outer periphery of the stopper, the absorber main body has a columnar shape, a thread is formed on an outer periphery of the absorber main body, the stopper is screwed in a threaded hole of the workpiece transferring device such that the stopper can move forward and rearward by rotation, the stopper can be fixed in an arbitrary position by a locknut screwed on the thread on the outer periphery, the absorber main body is screwed in the stopper such that a tip end portion and a rear end portion of the absorber main body projects outside from the stopper, and the absorber main body can be fixed in an arbitrary position by a locknut screwed on the thread on the outer periphery at the rear end portion.
As the transferring device, there is a rodless cylinder, for example.